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How solar power systemswork
Solar Cells
A solar panel is made of several photovoltaic cells. The cells are very thin, about 1/100th of an inch thick and usually 3 to 4 inches square. These cells convert sunlight to energy by the photovoltaic effect (we will discuss this effect in detail in a later article). These cells do not require fuel and have a standard lifetime of 20-30 years.
Bright Idea: To get your hands on a solar cell, take apart an old solar powered calculator. The small solar cell is what we call a thin-film cell and its operation is surprisingly compact and simple. For more information on thin film and how it might just be the answer to our renewable energy needs, see the last chapter of this book.
Solar Panels & Modules
Photovoltaic (PV) cells are assembled together to create a solar module. The module is what you are used to seeing as a panel. It has anywhere from 2 to 200 cells assembled together, encased in tempered glass and aluminum to make them weather resistant.
The solar food chain
Tying Them Together
Like batteries, cells can be combined in series or in parallel to create larger and more specific voltages and amperages. For instance, four 1-volt/1-amp cells in series will combine for 4 volts, but the amperage will stay at 1 amp. By contrast, four 1-volt/1-amp cells in parallel will maintain 1 volt but have 4 amps of output. You can multiply the amperage by the wattage (in the example above 4 x 1) to get the watts generated.
Parallel wiring means that the if two cells are side by side the positive ends are connected to each other, and the negative ends are connected to each other. To connect cells in series, you connect the negative of one to the positive of another.
Sizes and Shapes
Modules can be made in a many sizes and shapes to fit their application. Panels come in standard rectangular, triangular, fold-able, and even rolls. This means they can be used in a wide variety of applications, from boats and recreational vehicles to electric cars and space stations.
The Solar Array
Modules are combined to create solar arrays. An array is a group of modules assembled together and designed to meet a certain electrical load. You've probably seen most arrays mounted on the rooftops of homes. These arrays are designed to generate a certain amount of electricity over the course of a year given the angle and installation.
Efficiencies
Generally solar modules convert about 10-15% of the energy that strikes them into electricity. This means that for every 100 units of energy that actually hit the panel, only 15 of them actually enter the home as electricity. This is the biggest area of research now, as scientists recognize that significant advancements in solar efficiency will lead to cheaper solar energy.
